The FlashCopy function creates a point-in-time copy of data stored on a source volume to target volume.
In its basic mode, the FlashCopy® function copies the contents of a source volume to a target volume. Any data that existed on the target volume is lost and is replaced by the copied data. After the copy operation has completed, the target volumes contain the contents of the source volumes as they existed at a single point in time, unless target writes have been processed. The FlashCopy function is sometimes described as an instance of a time-zero copy (T 0) or point-in-time copy technology. Although the FlashCopy operation takes some time to complete, the resulting data on the target volume is presented so that the copy appears to have occurred immediately.
Although it is difficult to make a consistent copy of a data set that is constantly updated, point-in-time copy techniques help solve this problem. If a copy of a data set is created using a technology that does not provide point-in-time techniques and the data set changes during the copy operation, the resulting copy might contain data that is not consistent. For example, if a reference to an object is copied earlier than the object itself and the object is moved before it is copied, the copy contains the referenced object at its new location, but the copied reference still points to the previous location.
More advanced FlashCopy functions allow operations to occur on multiple source and target volumes. FlashCopy management operations are coordinated to provide a common, single point-in-time for copying target volumes from their respective source volumes. This creates a consistent copy of data that spans multiple volumes. The FlashCopy function also allows multiple target volumes to be copied from each source volume. This can be used to create images from different points in time for each source volume.